Two people have been arrested in Dublin's north inner city and gardaí used pepper spray on protesters after what they called a "co-ordinated and concerted effort to physically breach" a cordon near the port tunnel this afternoon.
It is understood it was a pro-Palestine protest.
In a statement this afternoon, gardaí said a public gathering moved towards Dublin Port Tunnel, which led to a cordon being put in place to prevent the protesting blocking the tunnel.
Gardaí attempted to engage with the protesters to disperse the protest in "a voluntary manner", which led to an attempt to get by the cordon.
This led to gardaí deploying an "escalation of response".
"Members of the Garda National Public Order Unit, dressed in ’soft cap’ uniform, supported by frontline uniformed Gardaí, intervened to prevent a breach of the Garda cordon which included the use of incapacitant spray on protesters," the statement said.
Two people were arrested for public order offences and have been brought to garda stations in the Dublin region.
The protest later dispersed and gardaí say they are not aware of any injuries being reported.
"An Garda Síochána will be carrying out further investigations in relation to this public disorder incident," the statement added.
"There is a constitutional right to assemble peaceably, subject to statutory provisions."
